﻿using System;
using System.Collections.Generic;

    class Program
    {
        static int ReturnIndexOfEll(int[] arr)
    {
        int index = 0;
        for (int i = 1; i < arr.Length - 1; i++)
        {
            if (arr[i] > arr[i + 1] && arr[i] > arr[i - 1])
            {
                index = i;
                break;
            }
            else
            {
                index = -1;
            }
        }
        return index;

    }
        static void Main(string[] args)
        {
            int[] arr = { 1, 0,1, 1, 3 };
            Console.WriteLine(ReturnIndexOfEll(arr));
         
        }
    }

